Metal forming tool for longitudinally curving channel sectioned strips



Apnl 16, 1957 A H. K. SWITZER 2,788,832

METAL FORMING TOOL FOR LONGITUDINALLY CURVING CHANNEL SECTIQNED STRIPS Filed Oct. 15, 1954 3 Sheets Sheet 1 29 I JNVEN'TOR.

April 16, 1957 H. K. swlTzER 2,783,832

METAL FORMING TOOL. FOR LONGITUDINALLY CURVING CHANNEL SECTIONED STRIPS Filed Oct. 15, 1954 3 Sheets-Shae; 2

14 42 45 as 26 36 47 49 i 35 a s1 I I l l l A I LLU I I l- 34 5 I i: 21 SZ .Apnl 16, 1957 H. K. SWITZER METAL FORMING TOOL. FOR LONGITUDINALLY CURVING CHANNEL SECTIONED STRIPS 3 Sheets-Sheet 3 Filed Oct. 15, 1954 8'}, I I -$NV I'OR ATTOGVEXS.

United States Fatent METAL FGRMING T091. FGR LONGITUDINALLY CURVING CHANNEL SECTIGNED STRIPS Harold K. Switzer, Aiexandria, Ky.

Application October 15, 1954, Serial No. 462,467

7 Claims. (Cl. 153-56) This invention is directed to a hand operated tool which is adapted to be used for forming a bend in a strip of channel-shaped molding, of the type employed for finishing the edges of counter tops, sink drainboards, the tops of utility tables and of similar structures, the bend being one in which the face or web portion of the strip is on the outside of the curve.

More specifically, the present tool is designed to meet the need of cabinet makers, and particularly those who specialize in custom-built kitchen cabinet work, for a small, inexpensive molding strip bending tool which may be used on the job. The need has arisen because of the trend in the design of horizontal work surfaces for kitchens toward free-form shapes, which are credited with being more functional and more attractive than the conventional straight sided rectangular work surfaces. Obviously, the free-form shapes vary from installation to installation so that it is virtually impossible for a cabinet maker to keep on hand enough pre-fabricated bends to meet all needs. It has been found that the present tool, when used in conjunction with the metal forming tool discloses in copending application Serial No. 462,501, filed Ocotber 15, 1954, by means of which inside curves may be formed, a cabinet maker may form all of the curves and bends which he requires from his supply of straight lengths of channel molding. V

Specific objectives and advantages of the present tool will be readily apparent to those skilled in the art from the following description of the drawings in which:

Figure 1 is a top plan view of a metal forming tool incorporating the principles of the present invention.

Figure 2 is a side elevational view thereof.

Figure 3 is a cross sectional View taken on the line 33 of Figure 2.

Figure 4 is a cross sectional view taken on the line 4-4 of Figure 1. V

Figure 5 is a perspective view showing a short length of the channel-shaped molding strip which the tool of this invention is adapted to bend and a preferred form of die pad used with the tool. 7

Figure 6 is a diagrammatic cross sectional view looking down on the forming rollers of the tool showing a length of molding strip at the start of a bending operation.

Figure 7 is a diagrammatic cross sectional view taken on the line 77 of Figure 6.

Figure 8 is a view similar to Figure 6 showing the molding strip in the process of being bent.

Figure 9 is a perspective view showing a length of molding strip after being bent by the present tool.

The molding strip which the present tool is designed to operate upon is configurated to embrace the edge of a countertop or similar structure and is known in the trade as no-drip stainless steel channel molding. It comprises a vertical web 10 which covers the outer edge of the countertop; a lower flange 11, which is turned inwardly at right angles to web 10 and which embraces the underside of the countertop; and, a flange 12, at the top of the strip, which also is turned at right angles to 2,788,832 Patented Apr. 16, 1957 web 10 and extends over the surface of the countertop adjacent to the edge thereof. The inner marginal edge of flange 12 is turned downwardly as at 13, at approximately 45, to provide the no-drip edge which gives the channel strip its name. The strip is made of stainless steel which is approximately .003 to .005 inch thick.

The present tool is adapted to form outside bends only, that is, bends in which the web portion of the channel strip is on the outside of the curve. Obviously, in making such a bend, the web must stretch or the two flanges must shrink. As a practical matter, the tension forces which stretch the web create a serious problem, because such forces tend to cause the web in the area of a bend to bow inwardly. As will be seen this problem is overcome in the present tool.

The tool comprises three basic elements which actually contact and form the strip during a bending operation. These elements are; a male forming roller 14, a female forming roller 15, and a pair of pressure die plates indicated generally at 16. In the present tool the position of the female forming roller 15 does not change, but provision is made to adjust the positions of the die plates and the male forming roller 14 relative to one another and to the female forming roller.

The two forming rollers and the die plates are mounted upon and are supported by a base which is designated 17. The base is in turn secured to a mount plate 18 by means of which the tool may be secured to a work bench. As a fabrication expedient, base 17 is made in two parts which are secured together adjacent to their respective ends by means of bolts 1919. The two parts, of the base are spaced from one another along the center.

line thereof as may be seen in Figure 3. Cooperating grooves in the faces of the two parts along the center space are provided to clamp in place a nut 20, which is adjacent to the left end of the tool as viewed in Figure 4, a post 21, which is adjacent to the right end thereof, and a second post 22, which. is spaced inwardly from the right end of the tool and which constitutes the means for journalling the female forming roller 15. The upper ends of the two posts 21 and 22 may be rigidly joined by a removable tie bar such as that indicated at 23.

if desired, an additional pair of bolts similar to bolts 19 may be employed at the respective opposite sides of post 22 to insure that the post is held securely in place. The additional bolts appear in cross section in Figure 4. A stud 24 which depends from the underside of post 22 may be received in an appropriate bore in mounting plate 18 to further rigidify the post. Stud 24 in conjunction with a pair of bolts 25 securely afiix the two parts of the base relative to mount plate 18.

The male forming roller 14 is rotatably mounted upon an adjustable carriage 26 which is movable longitudinally of the base toward and from the female forming roller 15. The carriage journals a post 27 which traverses a bore passing vertically through the center of the roller. The lower end of this post is of reduced diameter and is seated within an appropriate bore 28 in carriage 26. Beneath the carriage 26, post 27 is provided with a threaded stud 2 which extends through the space between the two parts of base 17 and below the base where a cap nut 36 is engaged upon it. The latter nut has a cross pin 31 therein to assist in the tightening of the nut. As will be seen in Figure 4 such tightening engages the upper end of nut 3i) tightly against the underside of the two parts of the base at the respective sides of threaded stud 29. This pulls the post 27 downwardly so as to clamp it and carriage 26 securely in place on the base. The nut 20 previously referred to extends above base 17 and is bored and tapped in the upper portion 32 thereof to receive an adjustment screw 33. The outer end of screw 7 33 has a cap 34tthereon which journals a cross pin ,35

Z9-to maintain carriage '26 .in positionon base 17. The

adjustment screw33 also resides within slot 36 so that the innerzend thereof may abut the inner end 37 of the slot to apply pressure for moving the carriage toward the female forming roller. V

The male forming roller 14 which is rotatably mounted upon post 27 hasa profile approximating the cross section of the channel-shaped molding strip which the tool is-adaptedtobend. 'lnoperationthe flange ii of the strip is :engagedunderneath the lower marginalcdge of the male formingroller-and the upper flange i2 is receivedin agroo-ve '38 which extends entirely around the roller being wide and deep enoughto accommodate the no-drip-edge 13 without binding.

Although it is considerably exaggerated in the drawings for illustration pun poses, the outer face of the male forming roller between annular groove 38 and the lower edge of the roller is bowed outwardly. This bowed or crowned portion of themale forming roller 14 contacts the inner face of the Web '14) ofthe channel-shaped molding strip and is designed to ofiset the tendency for the web to bow inwardly when being bent into a curve which requires the web to be stretched. It is found that a curvature for the face in whichthe crown is approximately .02 inch radially outwardly from the lower edge of the roller and the lower edge of groove 38 is sufi'icient. The tension'stresses in the bent web cause it to spring back to straight condition when it is removed from the tool.

The female forming roller 15, in the instance shown,

is made in three parts which are; an upper flange 4%), a lower flange 41 and a hub 42. The respective opposite ends of the hubare of reduced diameter and are engaged in appropriate bores in the respective flanges 4t? and 41. Rims provided at the opposite ends of the hubs are spun over as at 4343 to lock the two flanges securely in place. Both flanges are circular, however, whereas flange 40 is stiff and unyielding to the forces encountered in the bending operation, flange 41 is machined to taper outwardly from the hub to a relatively thin outer edge.

.This permits flange 41 to spring outwardly slightly forpurposes which will be explained below.

' The pressure die plates 16 are hinged to an adjustable carriage 44. This carriage has a pair of arms 45-45 at the inneror left end thereof which straddlerthe hub 42 of the female forming roller. The dierplates 16 are of substantially identical construction and are hinged to the outer ends of arms 45-45 and extend toward one another between the hub 42 and the crowned face of the male forming roller 14. Each plate is made of heavy spring steel so that it may yield under pressure to conform to the shape of the crowned face. In operation the inner ends of the two hinged die plates rest against the periphery of hub 42 (see Figures 6 and 8). The two inner edges of the die plates where such contact is made may be rounded off as indicated at 46. To increase the tendency for thetwo plates to bow and thereby conform to the configuration of the bend and the male forming roller, the plates may be weakened by drilling holes through them such as those shown at 47, there being three in each plate, one above the other in this instance. The outer end of each die plate 16 may mount a pair of blocks 48, one at the upper end and one at the lower end of each plate, and these blocks drilled to receive a hinge pin .49, the pin traversing an appropriate bore in the outer end of the arm 45 of the carriage 44. The right end of adjustable carriage-44 has a slot therein which is similar to the slot 36 in the carriage 26. This slot is indicated at;50 and its edges embrace'post 21 which serves to guide and align the carriage. Post 21 is drilled and tapped torreceiveansadjustment screw'51 which is similar show the tool in use.

able carriages 26 and ,44 are backed away from oneanto adjustment screw 33 located at the opposite end of the tool, including a cap '52 and a cross pin53. It will be seen that tightening of the adjustment screw 51 advances carriage 44 toward the left to move the respective die plates 16 away from the hub 42 of the female forming roller. So long as pressure is placed against the two die plates to hold their respective inner ends against hub 42, such adjustment has the effect of decreasing the angle between the plates. It isthis angle which determines to a large degree the curvature obtained in making a bend with the tool.

Reference isnow made to Figures 6, 7 and8 which As afirst step 'both'of 'the adjust:

other. This moves the male forming roller 14 away from the female forming roller and it pulls the two pressure die plates 16 into the position shown in Figure 6 in which they form an angle of 180. The length. of molding strip to be bent is then placed against the crowned face of the'male forming .roller with channel 12 .and'its nodrip edge 13 engaged in the annular groove 38. The lower flange 10 goes underneath the edge of the male forming roller. In orderto .protect the outer face of the web 10 during'the forming operation a pad 54 is provided which mayrcomprise a strip of flexible plastic material such as that whicheis soldunder the trade name Formica. The. pad may be as long as desired although it is found that the edges of the holes 47 in vthe two pressure die platesebite into ;the back face. of the pad and prevent it from moving olf of these plates. The pad should be wide enough to cover the web 10 of the strip.

a With the strip of molding engaged against the male forming roller, adjustment screw 33 may be employed to advance the. male forming roller into the space between the two flanges .49 and 41 of the female forming roller. This is a forced-fit. For example, the distance between the innerface of flanges 40 and 41 may be 1.750 inches.

' The overall height of the forming roller then should be approximately 1.730 inches so that clearance between the flanges and the underside of the male forming roller is only .020 inch. This is less than the thickness of the metal which isused in the flange 11. Thus, for .the male forming roller to fitinto the female forming roller with a strip of molding in place, the lower flexible flange 41 must give.

The position of the female forming roller '15 on base 17 is fixed. The male forming roller .is advanced to the position shown in Figure 6 wherein the pressure die plates 16. extend straight across the space between the two forming rollers .and the male forming roller is exerting a slight pressure against the inside of. web 10 of the molding strip. The cap. nut 30 then may be tightened to lock the male roller in place. Inasmuch as the inner position of the .,male forming roller is a fixed one relative to the base, guide marks such as those indicated at 55, on carriage 26 and 56 on base 17 may be employed to serve as an indicator of the. correct inner;

position of the forming roller 14. The degree of bend or radius -of the bend made :in the strip is determined primarily by'the position of angulation of the pressure die plates. Thus, starting with'the plates in the straight position of Figure 6, the adjustment screw, 51 is employed'to force the carriage 44 inwardly to change'the 'angulation of the plates with respect to one another. With the male and female forming rollers in fiXed'positions relative to one another and to thejbase, thedegree of angulation of the plates 'and the resulting radius of the bend being made may be indicated'directly upon the cap'52 of theadjus ting screw '51. Alternatively a dial or other indicatorscale maybe employed.

Toforma bend of desired size and shape, -a piece of straight stock molding strip is selected and the length of the arc in the-area where it is to be bent-is measured and marked directly upon the strip. The strip, is set arssasa the bend is at one side thereof and the part of the strip to be bent extends between the roller and out of the p- .posite side of the tool. The male forming roller is then rotated to roll the portion to be bent between the two forming rollers. The turning motion may be imparted to the male forming roller by means such as the socket wrench shown at 57. It will be noted that the post 27 extends above the male forming roller and that the wrench has a hollow center to engage over the extended end of the post. The underside of the socket wrench surrounding post 27 has a plurality of pins 58 depending therefrom which are designed to flt into cooperating bores 59 made in the upper face of the male forming roller, three such bores being shown in the present instance. An elongated handle 60 on the socket wrench is provided to apply the force necessary to feed the strip between the two forming rollers. 'It will be obvious that means other than the socket wrench shown may be employed if desired.

The bend is made progressively, preferably in not more than three or four passes of the strip between the two dies. In the first pass the adjustment screw 51 is turned in to a point which will form approximately thirty percent of the bend contemplated. With this setting the strip may be run between the rollers from one end of the area to be bent to the other. On the return pass the adjustment screw 51 may be tightened to shorten the radius of the bend. The same thing is done on the third pass through the two dies. A fourth pass may be used if necessary to bring the curve into exact size. It is suggested, however, that care be exercised in keeping the number of passes of the strip through the dies to a minimum, because stainless steel will work harden after five or six passes through the tool and tend to split.

Both forming rollers turn during the bending operation. The force fit of the lower flange of the molding strip between the underside of the male forming roller and the upper surface of the flexible flange 41 constitutes a friction drive from one roller to the other. The force flt does two things. The lower flange of the strip is constantly being ironed during the bending operation so that it cannot buckle. In addition, the flange 11 is held tightly in place between the two rollers so that the strip cannot slip. After the bend has been completed the lock nut 30 may be backed off of the threaded stud 29 and screw 33 run out so that the male forming roller 14 may be pulled away from the female forming roller to release the strip.

Having described my invention, 1 claim:

1. A hand tool for forming an arcuate bend in a strip of channel-shaped molding in which the web portion of the strip is on the outside of the curve, said strip having a flat lower flange thereon which is disposed at right angles to said web portion and having an upper flange thereon which is turned at right angles to the web portion and then downwardly at an angle adjacent to the free edge thereof, said tool comprising a male forming roller, a female forming roller, a pair of pressure die pads, the periphery of said male forming roller having a profile which approximates the profile of the channel-shaped molding strip to be bent, including an annular groove adapted to receive the upper angulated flange of said strip, said annular groove being spaced upwardly from the lower edge of said male forming roller such that the lower flange of the channelshaped molding strip may be engaged under the lower edge of said male forming roller when the upper flange is engaged in said groove, the annular area of said male forming roller between said groove and the lower edge of the roller being bowed outwardly to provide a slight crown which engages the inner face of the web portion of said channel-shaped strip when the flanges thereof are engaged as aforesaid, said female forming roller comprising a hub portion having two circular flanges aflixed thereto in spaced parallel relationship, the distance between the respective circular flanges being greater than the overall height of said male forming roller but less than the overall height of the male forming roller plus the thickness of the metal of which the channel-shaped molding strip is made such that the male forming roller having a strip engaged thereon must be forced into the space between the two circular flanges, the circular flange of the pair which makes contact with the lower channel flange engaged under the lower edge of said male forming roller when said male forming roller is forced between said circular flanges being thinner than the other circular flange of the pair to yield and thereby accommodate the force flt of the male forming roller between the respective circular flanges, means mounting the respective pressure die plates so that said plates extend toward one another from opposite sides of the hub of the female forming roller to have their respective inner ends resting against said hub, said plates being hingedly aflixed to the latter named means whereby movement of said means away from said hub and toward said male forming roller when said male forming roller is engaged between the circular flanges as aforesaid decreases the angle between said plates and thereby provides a pressure die of adjustable contour for forming bends 'of various radii between the respective forming rollers.

'2. A hand tool for forming an arcuate bend in a strip of channel-shaped molding in which the web portion of the strip is on the outside of the curve, said strip having a flat lower flange thereon which is disposed at right angles to said web portion and having an upper flange thereon which is turned at right angles to the web portion and then downwardly at an angle adjacent to the free edge thereof, said tool comprising a male forming roller, a female forming roller, means to forcibly move said male forming roller toward said female forming roller, the periphery of said male forming roller having a profile which approximates the profile of the channelshaped molding strip to be bent including an annular groove adapted to receive the upper angulated flange of said strip, said annular groove being spaced upwardly from the lower edge of said male forming roller such that the lower flange of the channel-shaped molding strip may be engaged under the lower edge of said male forming roller when the upper flange is engaged in said groove, the annular area of said male forming roller between said groove and the lower edge of the roller being bowed outwardly to provide a slight crown which engages the inner face of the web portion of said channel-shaped strip when the flanges thereof are engaged as aforesaid, said female forming roller comprising a hub portion having two circular flanges aflixed thereto in spaced parallel relationship, the distance between the respective circular flanges being greater than the overall height of said male forming roller but less than the overall height of the male forming roller plus the thickness of the metal in the lower flange of the channel-shaped molding strip such that the male forming roller having a strip engaged thereon as aforesaid must be forced into the space between the two circular flanges, the circular flange of the pair which makes contact with the said lower flange adapted to spring outwardly to accommodate the force fit of the male forming roller between the respective circular flanges, a pair of pressure die plates made of spring metal, means mounting the respective pressure die plates such that said plates extend toward one another from opposite sides of the hub of the female forming roller to have their respective inner ends resting against said hub, said plates being hingedly affixed to the latter named means whereby movement of the latter named means away from said hub and toward said male forming roller when said male forming roller is engaged between the circular flanges as aforesaid decreases the angle between said plates and thereby provides a pressure die 

